CN103346199A - Ultraviolet photoelectric detector and preparation method thereof based on single-layer graphene/zinc oxide nano-rod array schottky junction - Google Patents

Abstract

The invention discloses an ultraviolet photodetector based on a single-layer graphene/zinc oxide nanorod array Schottky junction and a preparation method thereof, which is characterized in that an N-type silicon base layer is used as a substrate, and A zinc oxide nanorod array is grown along the vertical direction, and an insulating layer is covered on the upper surface of the zinc oxide nanorod array, and the area of the insulating layer is 1/4 to 1/3 of the area of the zinc oxide nanorod array; on the insulating layer It is covered with single-layer graphene, a part of the single-layer graphene is in contact with the insulating layer, and the remaining part is covered on the zinc oxide nanorod array; a metal electrode layer is arranged on the single-layer graphene. The invention has simple process, is suitable for large-scale production, can prepare an ultraviolet photodetector with low cost, no pollution and strong light detection ability, and lays a foundation for the application of graphene and zinc oxide nanostructures in the ultraviolet photodetector.

Description

Ultraviolet photodetector based on single-layer graphene/zinc oxide nanorod array Schottky junction and its preparation method

technical field

The invention relates to an ultraviolet photodetector, in particular to an ultraviolet photodetector based on a nanomaterial Schottky junction.

Background technique

A photodetector is a device that converts light radiation into electricity, and it uses this feature to perform display and control functions. Ultraviolet photodetector is a device for detecting ultraviolet light, which plays a big role in people's daily life and even in military affairs. In life, it can be used in the fields of ultraviolet measurement in ultraviolet water purification, combustion engineering and flame detection, and ultraviolet detectors are also indispensable instruments in the fields of modern medicine and biology. In the military, ultraviolet detectors also play a very important role. Ultraviolet detection technology can be used in fields such as ultraviolet warning, ultraviolet communication, ultraviolet guidance, and ultraviolet interference. Therefore, many countries have conducted a lot of research on ultraviolet detectors to prevent military threats.

Since the energy of ultraviolet light is larger than other energies, zinc oxide, a wide-bandgap semiconductor material, has excellent physical properties and potential technical advantages. Using them as devices has higher power than silicon, high temperature, high frequency and short wavelength applications. The superior characteristics of devices such as gallium nitride make them have better development prospects in the field of ultraviolet detection. However, the photodetector with ZnO nanostructure is affected by the carrier depletion layer on the surface of the nanostructure, which leads to a slow detection speed.

Graphene, a monoatomic layer film composed of carbon atoms in a hexagonal honeycomb lattice, is one of the hottest materials at present, due to its many excellent physical properties, such as high electrical conductivity, ultra-high mobility and high transparency Therefore, graphene combined with various zinc oxide nanostructures has been successfully fabricated into high-efficiency photovoltaic devices, high-sensitivity gas sensors, transparent and sensitive field emitters, and supercapacitors. Despite some progress in these areas, graphene-modified ZnO nanostructured UV photodetectors have not been investigated.

Contents of the invention

The present invention is to avoid the shortcomings of the above-mentioned prior art, and to provide a Schottky junction based on single-layer graphene/zinc oxide nanorod arrays with low cost, no pollution, fast response speed, and strong light detection ability. UV photodetectors.

The present invention adopts following technical scheme for solving technical problems:

The present invention is based on a single-layer graphene/zinc oxide nanorod array Schottky junction ultraviolet photodetector, which is characterized in that: the N-type silicon base layer is used as the substrate, and the upper surface of the N-type silicon base layer A zinc oxide nanorod array is grown along the vertical direction, and the upper surface of the zinc oxide nanorod array is covered with an insulating layer, and the area of the insulating layer is 1/4 to 1/3 of the area of the zinc oxide nanorod array. 3. The boundary of the insulating layer does not exceed the boundary of the zinc oxide nanorod array; the insulating layer is covered with a single-layer graphene, a part of the single-layer graphene is in contact with the insulating layer, and the remaining part covers On the zinc oxide nanorod array, the boundary of the single-layer graphene does not exceed the boundary of the zinc oxide nanorod array; a metal electrode layer is arranged on the single-layer graphene, and the metal electrode layer and the The single-layer graphene is in ohmic contact, and the boundary of the metal electrode layer does not exceed the boundary of the insulating layer.

The present invention is based on the ultraviolet photodetector of monolayer graphene/zinc oxide nanorod array Schottky junction, and its feature also is: described metal electrode layer is silver paste electrode or gold paste electrode; The thickness of described metal electrode layer is 10-30μm.

The N-type silicon base layer adopts an N-type heavily doped silicon wafer with a resistivity of 0.0002-0.001Ω/cm.

The insulating layer is insulating tape.

The diameter of each zinc oxide nanorod in the zinc oxide nanorod array is 200nm˜1000nm.

The present invention is based on the preparation method of the ultraviolet photodetector of monolayer graphene/zinc oxide nanorod array Schottky junction, and its characteristic is to carry out according to the following steps:

a. Take an N-type heavily doped silicon wafer with a resistivity of 0.0002～0.001Ω/cm as the N-type silicon base layer. 99.999% zinc oxide powder and graphite powder with a purity of 99.9% to 99.99% are used as raw materials, and zinc oxide nanorod arrays are prepared on the N-type silicon base layer, and after natural cooling to room temperature, the zinc oxide nanorods grown on them are taken out. An N-type silicon base layer of the array;

b, using insulating tape as an insulating layer to paste and cover 1/4 to 1/3 of the area of the zinc oxide nanorod array grown in step a;

c. Lay single-layer graphene on the insulating layer prepared in step b, a part of the single-layer graphene is in contact with the insulating layer, and the remaining part covers the zinc oxide nanorod array, and the single-layer graphene The boundary of does not exceed the boundary of the zinc oxide nanorod array;

d. Applying a metal electrode layer on the single-layer graphene, the boundary of the metal electrode layer does not exceed the boundary of the insulating layer.

Compared with the prior art, the beneficial effects of the present invention are reflected in:

1. The present invention designs an ultraviolet photodetector based on single-layer graphene/zinc oxide nanorod array Schottky junction, which has low cost, no pollution, strong light detection ability, simple process, and is suitable for large-scale production. The application of graphene and zinc oxide nanostructures in the field of ultraviolet photodetectors has laid the foundation;

2. The ultraviolet photodetector of the present invention introduces single-layer graphene to replace the metal thin layer in the traditional photodetector, avoiding the use of large-scale equipment such as electron beam coating and magnetron sputtering, and reducing the preparation cost;

3. The present invention makes full use of the advantages of the large light-trapping effect of the zinc oxide nanorod array structure, overcomes the large reflection shortcomings of traditional thin-film photodetectors, and avoids the extra cost brought by the use of anti-reflection layers increase.

Description of drawings

Fig. 1 is the structural representation of the ultraviolet photodetector based on monolayer graphene/zinc oxide nanorod array Schottky junction of the present invention;

Fig. 2 is the current-voltage characteristic curve of the UV photodetector based on single-layer graphene/zinc oxide nanorod array Schottky junction prepared in embodiment 1 of the present invention under no light and 365nm ultraviolet light irradiation;

Fig. 3 is that the single-layer graphene/zinc oxide nanorod array Schottky junction type ultraviolet photodetector prepared by the embodiment 1 of the present invention works under -5V, and ^the ultraviolet light of 365nm, light energy is 100μW/cm Photoresponse curves of the device under light-on and light-off conditions;

Labels in the figure: 1N-type silicon base layer; 2ZnO nanorod array; 3Insulation layer; 4Monolayer graphene; 5Metal electrode layer.

Detailed ways

Example 1

Referring to Fig. 1, the present embodiment is based on the ultraviolet photodetector of monolayer graphene/zinc oxide nanorod array Schottky junction and has following structure: with N-type silicon base layer 1 as substrate, in N-type silicon base layer The upper surface of 1 is grown with zinc oxide nanorod array 2 along the vertical direction, and the upper surface of zinc oxide nanorod array 2 is covered with insulating layer 3, and the area of insulating layer 3 is 1/4 of the area of zinc oxide nanorod array 2 to 1/3, the boundary of the insulating layer 3 does not exceed the boundary of the zinc oxide nanorod array 2; the insulating layer 3 is covered with a single-layer graphene 4, a part of the single-layer graphene 4 is in contact with the insulating layer 3, and the remaining part is covered on the On the zinc oxide nanorod array 2, the boundary of the single-layer graphene 4 does not exceed the boundary of the zinc oxide nanorod array 2; on the single-layer graphene 4, a metal electrode layer 5 is arranged, and the metal electrode layer 5 and the single-layer graphene 4 In ohmic contact, the boundary of the metal electrode layer 5 does not exceed the boundary of the insulating layer 3 .

In the present embodiment, the preparation method of the ultraviolet photodetector based on the single-layer graphene/zinc oxide nanorod array Schottky junction is carried out as follows:

a. Take an N-type heavily doped silicon wafer with a resistivity of 0.0005Ω/cm as the N-type silicon base layer 1, and in a vacuum tube furnace, under the temperature condition of 1000°C, oxidize it with a purity of 99.999%. Zinc powder and graphite powder with a purity of 99.9% are used as raw materials to prepare zinc oxide nanorod arrays 2 on the N-type silicon base layer 1. After cooling to room temperature naturally, the N-type silicon oxide grown with zinc oxide nanorod arrays 2 is taken out. The base layer 1; the diameter of each zinc oxide nanorod in the zinc oxide nanorod array 2 is 400 nm.

The N-type heavily doped silicon wafer with low resistivity is selected to ensure that it forms an ohmic contact with the ZnO nanorod array, and the smaller the resistivity, the better the effect. The range of 0.0002～0.001Ω/cm is the optimal range considering all factors comprehensively.

b. Use insulating tape as the insulating layer 3 to paste and cover 1/4 of the area of the zinc oxide nanorod array 2 grown in step a;

C, pave single-layer graphene 4 on the insulating layer 3 prepared in step b, the area of single-layer graphene 4 is greater than the area of insulating layer 3, a part of single-layer graphene 4 is in contact with insulating layer 3, and remaining part is covered on the On the zinc oxide nanorod array 2, the boundary of the single-layer graphene 4 does not exceed the boundary of the zinc oxide nanorod array 2; the single-layer graphene directly contacts with the zinc oxide nanorod array 2 to form a Schottky junction.

D, smear silver paste electrode on single-layer graphene 4, the boundary of silver paste electrode does not exceed the boundary of insulating layer 3, also can smear gold paste electrode or other electrode that is ohmic contact with single-layer graphene here as metal electrode Layer 5.

The purpose of the insulating layer 3 is to ensure that the metal electrode layer 5 will not contact the zinc oxide nanorod array 2 through the single-layer graphene 4, so as to cause device failure.

The characteristic curves of the relationship between current and voltage of the ultraviolet photodetector based on the single-layer graphene/zinc oxide nanorod array Schottky junction prepared in this example under the absence of light and the irradiation of 365nm ultraviolet light are shown in FIG. 2 . It can be seen from the figure that the prepared device exhibits typical Schottky rectification characteristics in the absence of light, and when irradiated by ultraviolet light with a wavelength of 365nm and a light energy of 100μW/ ^cm2 , an obvious photocurrent is generated, confirming that the device It has very superior photodetection characteristics.

Fig. 3 is the photoresponse curve of the ultraviolet photodetector prepared by the present embodiment with the ultraviolet light having a wavelength of 365nm and a light energy of 100 μW/ ^cm2 as the light source, and switching the light source under the voltage of -5V; as can be seen from the figure, the device The two states of high conductance and low conductance are reflected stably and reproducibly.

Claims (6)

1. based on the UV photodetector of single-layer graphene/nanometic zinc oxide rod array schottky junction, it is characterized in that: with N-type silicon substrate layer (1) as substrate, vertically growing at the upper surface of described N-type silicon substrate layer (1) has nanometic zinc oxide rod array (2), upper surface at described nanometic zinc oxide rod array (2) is coated with insulating barrier (3), the area of described insulating barrier (3) be described nanometic zinc oxide rod array (2) area 1/4 to 1/3, the border of described insulating barrier (3) does not exceed the border of described nanometic zinc oxide rod array (2); Be coated with single-layer graphene (4) at described insulating barrier (3), described single-layer graphene (a 4) part contacts with described insulating barrier (3), remainder covers on the described nanometic zinc oxide rod array (2), and the border of described single-layer graphene (4) does not exceed the border of described nanometic zinc oxide rod array (2); Single-layer graphene (4) is provided with metal electrode layer (5), and described metal electrode layer (5) is ohmic contact with described single-layer graphene (4), and the border of described metal electrode layer (5) does not exceed the border of described insulating barrier (3).

2. the UV photodetector based on single-layer graphene/nanometic zinc oxide rod array schottky junction according to claim 1, it is characterized in that: described metal electrode layer (5) is ag paste electrode or gold paste electrode; The thickness of described metal electrode layer (5) is 10～30 μ m.

3. the UV photodetector based on single-layer graphene/nanometic zinc oxide rod array schottky junction according to claim 1 is characterized in that: it is the N-type heavy doping silicon chip of 0.0002～0.001 Ω/cm that described N-type silicon substrate layer (1) adopts resistivity.

4. the UV photodetector based on single-layer graphene/nanometic zinc oxide rod array schottky junction according to claim 1, it is characterized in that: described insulating barrier (3) is insulating tape.

5. the UV photodetector based on single-layer graphene/nanometic zinc oxide rod array schottky junction according to claim 1, it is characterized in that: the diameter of each zinc oxide nano rod is 200nm～1000nm in the described nanometic zinc oxide rod array (2).

6. the preparation method of the described UV photodetector based on single-layer graphene/nanometic zinc oxide rod array schottky junction of a claim 1 is characterized in that carrying out as follows:

A, to get resistivity be that the N-type heavy doping silicon chip of 0.0002～0.001 Ω/cm is as N-type silicon substrate layer (1), in vacuum tube furnace, under the temperature conditions of 1000 ° of C, be that 99.99%～99.999% Zinc oxide powder and purity are that 99.9%～99.99% graphite powder is as raw material with purity, at described N-type silicon substrate layer (1) preparation nanometic zinc oxide rod array (2), after naturally cooling to room temperature, take out the N-type silicon substrate layer (1) that growth has nanometic zinc oxide rod array (2);

B, paste to cover as insulating barrier (3) with insulating tape step a growth nanometic zinc oxide rod array (2) area 1/4 to 1/3;

C, lay single-layer graphene (4) at the prepared insulating barrier of step b (3), described single-layer graphene (a 4) part contacts with described insulating barrier (3), remainder covers on the described nanometic zinc oxide rod array (2), and the border of described single-layer graphene (4) does not exceed the border of described nanometic zinc oxide rod array (2);

D, smear metal electrode layer (5) at single-layer graphene (4), the border of described metal electrode layer (5) does not exceed the border of described insulating barrier (3).

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